Polymeric materials exhibiting both thermoplastic, as well as elastomeric characteristics have a variety of unique properties which makes such materials valuable articles of commerce. Such thermoplastic elastomers are block copolymers having the general structure of ABA, or A(BA).sub.n where A is a thermoplastic, glassy block segment with a high glass transition temperature, while B is an elastomeric block. The copolymers behave like vulcanized rubbers at room temperature, and like thermoplastic polymers at higher temperatures. Thus, the materials can be melt extruded like plastics, while retaining their beneficial rubbery features upon cooling. This ability is not only of advantage during processing of the polymers, but allows the materials to be reprocessed as occasion demands. Furthermore, not only are such products fundamentally elastomeric in nature, but they exhibit physical behaviors similar to elastomers which have been reinforced with reinforcing agents. In other words, the products behave physically substantially in the same manner as vulcanized rubbers, but without the need to subject them to vulcanization procedures, which is often impractical because of the nature of the product being produced, for example, adhesives, coatings, and elastic threads.
Polymers having such dual nature have been known for some time, one such product, for example, being that prepared by copolymerizing polystyrene with polybutadiene, sold under the trademark "Kraton" by Shell Oil Company. Other similar products are disclosed in U.S. Pat. No. 4,242,471, which involve the polymerization of various conjugated dienes with certain other compounds. While the latter products possess the desirable fundamental duality of properties described, unfortunately, they also possess certain undesirable characteristics. For example, their glass transition temperatures are in many cases undesirably low, in the neighborhood of from 80.degree. C. to 90.degree. C., limiting the temperature environment in which they can be used. In addition, the products possess an undesirably high degree of unsaturation in their central polymer block portion which makes them vulnerable to degradation resulting from oxidation resulting through exposure to air. While such degradation may be avoided by subjecting the products to techniques which saturate their double bonds, the additional processing entails undesirable expense.